Flame retardant polycarbonate resins generally have good impact resistance. Accordingly, such resins have been widely used in automobile parts and electric or electronic products which require such properties, particularly parts requiring good flame retardance. Generally good flame retardance can be imparted to the polycarbonate resin using a halogen-containing compound as a flame retardant. This method has several advantages in that there is little deterioration in physical properties and it can easily provide flame retardance. However, because toxic gases harmful to a human body can be liberated upon combustion, the use of such a halogen-containing compound has been restricted in most countries in the world and thus the amount of such compounds used has been greatly reduced.
As one solution to overcome these problems, a phosphoric acid ester compound can be used as a flame retardant. In the case where a phosphoric acid ester compound is added to the polycarbonate resin, the flowability of the resin can improve, but the impact resistance and heat resistance of the resin can markedly decline. Thus, there still exists a problem in the application to products requiring high levels of heat resistance.